The field of the invention relates generally to bearings, and more specifically, to a method and a system for a fiber optic sensing device for detecting multiple parameters of a bearing.
The life of a ball bearing depends heavily on its operating thrust load. If loads are too high, bearing life may be significantly reduced. Likewise, when bearing loads are too low, skidding can occur leading to premature failure. Rotor thrust control through changing engine cavity pressure is one method of managing rotor thrust. To make changes effectively, in either an active or passive method, an accurate and reliable measurement instrument is needed.
Fiber optic sensors offer a reliable means of monitoring thrust. In addition, fiber optic sensors are substantially immune to the effects of electromagnetic interference (EMI), which offers a significant advantage over electrically-based strain gages, which tend to pick-up significant signal distortion during engine operation.
Thrust sensors on an engine enable an operator to integrate control schemes to minimize and/or mitigate adverse thrust reactions during engine operation, which can lead to extended bearing life, less downtime for engine overhauls, and a potential means for monitoring bearing health in real time. Strain gages are typically used to perform bearing thrust loading measurement. However, electrical resistance strain gage technology of the existing art encounters several problems and limitations. One problem encountered is that the strain gage indicated output is dependent upon its temperature environment at any thrust load, thus inducing errors into the measurement. In addition, the strain gages are subject to mechanical fatigue failure and, thus, loss of signal. Another problem is that the strain gages are subject to electrical magnetic interference or other induced electrical noise, thus inducing errors into the thrust load measurement. Yet another problem encountered is that the strain gages are not an absolute measurement, as they require an electrical tare balance and other thermal compensations. Also, the electrical resistance-based strain gage possesses a calibration constant known as the gage factor, which varies as a function of temperature and can produce an error in the indicated thrust measurement. The conventional technique also does not effectively address the issues relating to mitigation of thrust load on the bearings.